The effects of marine plastic pollution
While public perception of the effects of plastic in the oceans has been
formed by images of turtles and other marine fauna entangled in fishing lines
and plastic debris, the effects of marine plastic pollution are more widespread,
can be less visible and many are only now being identified. There also remain
significant gaps in knowledge about the effects of marine plastic pollution including
the population level impacts of ingestion, the effects on human health of
plastics in the food chain, and the frequency and potential effects of invasive
species via marine debris, as well as the effects of microplastics.
As the Australian Institute of Marine Science (AIMS) concluded:
The risks of marine plastic pollution to marine life,
ecosystems and fisheries are uncertain, and understanding them requires
detailed information on: (i) the likelihood of exposure to plastics and (ii)
the direct and indirect effects of the plastics. At present it is not possible
to rank the risks posed by marine plastic pollution in the marine environment
(internationally or nationally) against more comprehensively studied pressures
such as climate change or land-based pollution.
This chapter provides an overview of the effects of plastic pollution on
marine fauna (including ingestion and entanglement), human health, fisheries
and shipping, and ecosystems. It also identifies areas where more research is
Effects of plastic pollution on marine fauna
The committee received considerable evidence on the impact of plastic
pollution on marine fauna. This evidence included research from leading
Australian academics, government agencies and community organisations. The
evidence indicated that plastic pollution affects marine fauna and flora
the transport and bioaccumulation of harmful chemicals; and
the transport of invasive species.
Plastic ingestion has been documented in a large range of marine
species—the committee received evidence that over 200 species of marine animal
are recorded as having ingested manufactured polymers.
Dr Kathy Townsend told the committee that 'on a global scale Australia has been
recognised as a hot spot for marine debris ingestion for both seabirds and sea
AIMS added that, based on evidence from overseas studies, 'it is highly likely
that plastic ingestion is much more widespread and includes many more marine
species in northern Australia than currently documented'.
Studies indicate that plastic bags, cling film, food wrappers and
balloons are most commonly consumed by turtles, while seabirds consume degraded
hard plastics sourced from take away containers, single-use plastics and
discarded consumer products.
Dr Townsend explained that balloons are attractive to both seabirds and turtles
because they look similar to squid and jellyfish. Red and orange balloons are particularly
appealing to marine fauna as they are similar colours to traditional prey
Dr Hardesty added that matter adhering to the surface of plastic, such as
roe, may make objects attractive to seabirds.
The committee received evidence that plastic ingested by animals is
known to 'physically block their digestive tracts, alter feeding behaviour and
Plastic debris may also lacerate the mouth and digestive tract causing serious
injury to the animal. This may also result in a greater susceptibility to
predators and disease, and a decreased ability to breed and rear young.
However, the committee was also informed that the ability to assign
actual cause of death to plastic ingestion is 'exceptionally small.' Dr Britta
Denise Hardesty, CSIRO, explained that differentiation between causality and
correlation is 'really important' and that unless gut perforation or blockage
is identified, cause of death can be difficult to identify. Dr Hardesty also
commented that CSIRO is undertaking work to try to estimate how much plastic is
required to kill a turtle or a seabird.
The following discussion provides an overview of evidence received in
relation to ingestion of plastics by turtles, seabirds, cetaceans and corals
The committee received a range of evidence on the ingestion of marine
plastic pollution by turtles. In particular, the types of plastic consumed, the
species particularly susceptible to plastic consumption, and the rates of death
and injury as a result.
Dr Townsend stated that ingestion by turtles has been increasing
historically, with ingestion rates of over 60 per cent in some species of sea
turtles since 1980. It is also estimated that over 50 per cent of the world's
sea turtles have ingested marine debris worldwide as the population stands now.
Studies indicate that certain species are more likely to ingest plastic,
with oceanic leatherback turtles and green turtles being at the greatest risk
of both lethal and sub-lethal effects of ingesting plastic debris.
Dr Townsend indicated that younger turtles, at both the 'lost years-stage' and
at the 'benthic-stage', are particularly prone to plastic ingestion.
Research has found that smaller, oceanic-stage turtles are more likely to
ingest plastic debris than coastal foragers, and carnivorous species are less
likely to ingest debris than herbivores or gelatinovores (jellyfish eaters). The
CSIRO also found that benthic-stage turtles favour soft clear plastic, possibly
because it resembles jellyfish.
The CSIRO in collaboration with the University of Queensland, and the
Imperial College, London, identified that turtles are selective of materials
and prefer to ingest items 'that are flexible, and different in colour from the
background debris in the ocean'.
Dr Townsend also told the committee that:
...studies have shown that for turtles, for instance, things
such as plastic bags, cling film, food wrappers and balloons are the most
commonly consumed plastic debris, regardless of life stage.
Once plastic has been ingested by a turtle, the animals have difficulty
in ridding themselves of this debris—many turtles have downward facing spines
in their throats which prevent the regurgitation of plastic. The plastic
subsequently remains in the stomach where it blocks the digestion of food. In
addition, plastic products often decompose within the turtle and produce gas
which remains trapped inside the animal. These gases cause the turtle to float
on the surface of the water, which can lead to starvation, and the inability to
hide from predators.
According to the Wildlife Preservation Society of Queensland, recent
studies by the Queensland National Parks and Wildlife Service found that 'over
70% of loggerhead turtles found dead in Queensland waters have ingested
plastic'. In addition, 30 per cent of sea turtle deaths in Moreton Bay can be
attributed to the ingestion of plastic pollution.
The committee received evidence from a number of organisations that provide
rescue services for injured marine animals. For example, the Coolum and North
Shore Coast Care explained that within its organisation there are a number of
volunteers responsible for monitoring the nesting of endangered loggerhead and
green sea turtles, and who attend turtle strandings. It further stated that sea
turtles generally only strand when they are very ill or dead. It noted that in
the past three years, there have been a total of 134 strandings, with 71
deceased animals found.
Necropsies were undertaken on a number of these deceased turtles at the
University of Queensland Research Station. Data published by this facility in
2012 indicated that '33% of the sea turtles necropsied from the Brisbane and
Sunshine Coast areas had ingested plastic debris'.
Similarly, the Great Barrier Reef Marine Park Authority commented that plastics
make up 90 per cent of the marine debris ingested by marine turtles in
The Australian Seabird Rescue also noted that a database recording
marine turtle strandings on the coast of northern New South Wales recorded a
total of 142 strandings between 2001–2007. It indicated that of these
strandings, 18 turtles were listed as having ingested plastic.
However, the CSIRO stated that it is difficult to quantify the impact of
ingestion in turtles, and as a result, it is currently working to analyse the
relationship between ingestion and mortality. Preliminary results indicate that
there is a 'positive relationship' between the two, and the CSIRO is currently
collaborating with researchers at the University of Tasmania to estimate
Seabirds and shorebirds
Seabirds live their lives in the open ocean and most only return to land
to breed. Dr Hardesty commented that seabirds 'are truly pelagic...We consider
seabirds as the canary in the coalmine, if you will, in the oceans. It is a
really good indicator of ocean health'.
The committee received extensive evidence on the ingestion of marine
plastic by seabirds. This evidence included the effect of plastic ingestion on
both adult and juvenile birds, the rate of plastic consumption, and the future
direction of research in this field.
Seabirds ingest a variety of items, with Dr Townsend informing the
committee that seabirds largely consume 'balloons and degraded hard plastics,
usually sourced from things like takeaway containers, water bottles and other
single-use plastics and discarded consumer products'.
Other submitters also provide evidence of the types of plastic debris found in
seabirds. For example, Dr Hardesty reported seeing toothbrushes, bottle caps
and even glass bottles with metal lids inside albatross.
Dr Heidi Auman, submitted findings from her research and stated:
98% of Laysan albatross chicks from Midway Atoll National
Wildlife Refuge contained marine plastic debris in their stomachs. Most of this
could be measured in multiple handfuls and included: shards of unidentified
plastic, bottle caps, Styrofoam, beads, fishing line, buttons, chequers,
disposable cigarette lighters (up to six per bird), toys, PVC pipe and other
PVC fragments, golf tees, dish washing gloves, highlighter pens, medical waste
and light sticks. Non-plastic items included neoprene O-rings, rubber pieces,
and a lightbulb. Naturally killed chicks had significantly greater masses of
plastic and had significantly lighter body masses and lower fat indices than
injured but otherwise healthy chicks.
In addition, research shows that chicks of some species are being fed
plastic while in the nest. Mr Ian Hutton commented that studies showed 79 per
cent of flesh-footed shearwater chicks contained some ingested plastic, fed to
them by their parents who picked this debris up while foraging over the Tasman
In 2014, the CSIRO published the results of a global risk analysis of
seabirds and marine debris ingestion for nearly 200 species. It was found that
43 per cent of seabirds and 65 per cent of individuals within a species have
plastic in their gut.
The CSIRO predicted that 95 per cent of the world's seabirds will have
ingested plastic by 2050 due to the steady increase in plastics production.
The committee received evidence that the Tasman Sea, between Australia
and New Zealand and the Southern Ocean, has been identified as a 'hotspot' for
the potential impact of plastic ingestion by seabirds.
For example, a study conducted by the CSIRO identified that 67 per cent of
short-tailed shearwaters (Puffinus tenuirostris) were found to have
ingested marine plastic pollution. The study found that juvenile birds were
more likely to ingest plastic than adults, and that juveniles consumed larger
Dr Jennifer Lavers, who conducts research with Mr Hutton into the
flesh-footed shearwater (Puffinus carneipes) populations on Lord Howe
Island, told the committee that since 2005 there has been a gradual increase in
the amount of plastic and also the proportion of the population ingesting
plastics. Mr Hutton added that in one instance, 274 pieces of plastic were retrieved
from a deceased bird. Mr Hutton stated that this was a record and
represented '14 per cent of the body weight' of the bird.
Mr Hutton went on to note that this 'is the equivalent of a human carrying
a pillowcase full of plastic in...[their] stomach'.
The committee was interested to hear that plastic items retrieved from
the stomachs of seabirds on Lord Howe Island were able to be identified as
items originating from Australia rather than from overseas sources. In
particular, Mr Hutton told the committee that bottle lids, balloon clips, and
caps from milk cartons, marked with identifiable Australian brands are
regularly retrieved from the stomachs of birds.
Dr Lavers told the committee that seabirds such as the shearwaters on
Lord Howe Island have been found severely emaciated as a result of ingesting
large amounts of plastic. In addition, the ingestion of plastic has also been
found to affect the growth and development of juvenile birds. Dr Lavers told
the committee that on Lord Howe Island researchers:
...very regularly find very severely emaciated birds, so the
plastic has been linked with very significantly reduced body mass and also
stunted wing growth. These are birds that are attempting to make their first
flight out to sea with wings that are half the length of what they should be at
that age. You can imagine that their survivability is, as a result of that,
Dr Lavers also noted that despite research being available on the impact
of plastic ingestion on individual birds, there is a 'key research gap' in
understanding the 'population level impact'.
Dr Lavers did however provide the committee with 'a very rough estimate' that
the juvenile survival rate of shearwaters is reduced by 'approximately 11 per
The key research gap in understanding the effect of marine plastic
ingestion at the population level has been widely recognised by the scientific
community. Dr Hardesty noted that while there were many papers and stories
on individual species, there was a need to commence addressing the population
Similarly, Professor Tony Underwood, stated that modelling of populations is
not being undertaken and pointed to the work on the petrels in Europe. While
sampling is carried out to measure the amount of plastic ingested, there is no
improvement in understanding or any assessment of the risk to a species.
Dr Hardesty went on to comment that the CSIRO has developed a method to
allow assessment at the population level for seabirds. This is a non-invasive
method for measuring the amount of plastic in a seabird which examines the oil
secreted from a seabird's preening gland.
This method can be applied at the 'individual, population and species levels
and it has no observed detrimental impacts'.
Dr Hardesty described this research as an opportunity to address the issue of
marine plastic pollution 'holistically'.
Shorebirds, also known as waders, inhabit coastal margins around the
world. Resident shorebirds in Australia include the Hooded Plover and Pied
Oystercatchers. Approximately 60 species of migratory shorebirds visit
Australia including Sandpipers and Stints.
Shorebirds forage on coastlines around the world, both rocky and sandy
foreshores. Many species are visual foragers, that is, they visually locate
their prey on or in the sediments and beachcast seaweeds and grasses before
As with seabirds, concerns were raised about the ingestion of plastics
by shorebirds. The submission from Birdlife Australia focused on the potential
threat to resident and migratory shorebirds from the ingestion of microplastics
and the associated absorbed chemicals. Dr Eric Woehler, Convenor, Birdlife
Tasmania, argued that:
...every single shorebird that feeds on Australia's foreshore
or coastal areas would potentially be at risk from ingesting microplastics. It
is clear from the literature around the world that these microplastics are not
just confined to marine environments; they are also found in freshwater and
estuarine environments. These foreshore areas—estuarine, freshwater and
marine—are all used by migratory and resident shorebirds in Australia.
In particular, Birdlife Australia submitted that shorebirds may face
threats from marine microplastics through the ingestion of the particles
themselves that can remain in their stomachs and potentially accumulate over
time, and from the ingested microplastics that are likely to have absorbed persistent
organic pollutants and metals that can be transferred to the shorebirds' body
The effects of microplastics in the marine environment are canvassed in
more detail in the following discussion.
The committee received evidence that ingestion of plastic by cetaceans,
including dolphins and whales, can cause death and injury, particularly when plastic
causes fatal blockages in the animals' digestive tracts. Plastic products may
also lacerate digestive tracts or cause rupturing, which leads to the death of
An example of the ingestion of plastic by a whale, was provided by the
Boomerang Alliance: in August 2000, an eight metre Bryde's whale died soon
after stranding on a beach in Cairns. A subsequent necropsy found that its
stomach contained six square metres of plastic, including a large number of
lightweight single-use plastic bags.
However, Professor Underwood cautioned the committee against assuming
that ingestion of plastic caused death in every case of whale stranding.
Professor Underwood told the committee that 'very few...cases were autopsied' so
there is very little evidence of the 'biological consequences' of plastic
Dr Hardesty similarly told the committee that researching the
consequences of ingestion and entanglement on cetaceans was deemed important by
the Australian Government as they 'are really good indicators of ocean health'.
However, this work has not occurred yet.
Corals and zooplankton
The committee received evidence that in addition to large marine
animals, research indicates that corals and zooplankton also ingest marine
A number of submissions stated that the ingestion of microplastics poses
a threat to coral reefs. For example, Clean Up Australia submitted that corals
are non-selective feeders and readily consume microbeads and microplastics that
are present in seawater. Clean Up Australia went on to note that a study
conducted by the Australian Research Council Centre of Excellence for Coral
Reef Studies discovered that corals digest microplastics at almost the same
rate as normal food, and are unable to expel them from their digestive systems.
There is concern that eventually, corals will starve and die as their digestive
cavities are filled with plastic.
Further research is being undertaken to determine the impact plastic has on
coral physiology and health, as well as its impact on other marine organisms.
Research is also being conducted into the trophic (that is, from prey to
predator) transfer of plastics, and accumulated chemicals through the ingestion
of zooplankton. Birdlife Australia submitted that studies have found
microplastics present in planktivorous fish, which are fish that feed on
Birdlife Australia also stated that limited evidence from a small number
of studies has shown bioaccumulation of microplastics in seals from ingestion
of fish which have fed on zooplankton. However, the studies were not able to
demonstrate whether the zooplankton or the fish had ingested the plastic.
Evidence was presented to the committee on the threat of entanglement
posed by marine plastic pollution. Marine fauna entanglement in marine plastic
pollution includes entanglement in abandoned fishing gear such as nets and
lines, plastic bags, packing straps, ropes, clothing and diving gear, and
Entanglement can cause restricted mobility, scoliosis, starvation,
smothering and wounding, which in turns leads to infections, amputation of
limbs, and death. Entanglement can also reduce the ability to avoid predators.
Entanglement is a world-wide problem. Dr Townsend told the committee
Worldwide, at least 143 species of marine animals have been
entangled in marine debris, including most of the world's sea turtles. Locally,
in Moreton Bay, we have estimated that between six and seven per cent of the
animals are being entangled in marine debris. This plastic marine debris source
for entanglements is coming mainly from the fishing industry, both commercial
However, it has been noted by researchers that, to date, there is scant
data overall to provide a global estimate of the number of animals which have
become entangled. Vegter et al. observed that most reports are either
restricted to opportunistic observations of animals or are from heavily visited
coastal regions. The researchers concluded that 'we likely observe only a small
fraction of entangled or injured wildlife', thus actual or total rates of
wildlife entanglement are not known.
The committee received evidence that seabirds, turtles, whales,
dolphins, dugongs, sea snakes, sharks, fish, crabs and crocodiles and numerous
other species are killed and maimed through entanglement.
Eco Barge Clean Seas detailed an incident where a large, male green sea turtle
weighing 120 kg was found stranded on Whitehaven Beach in the Whitsunday
Islands. The animal was found with a 'completely amputated front left flipper
and wounds on the rear of its body.' It is assumed that these injuries were
sustained as a result of fishing line entanglement due to the depth and
cleanliness of the cuts. Eco Barge Clean Seas stated that it is likely the
animal either tried to rid itself of the fishing line or the line became
entangled in coral and the animal was forced to pull itself free in order to return
to the surface to breathe. Eco Barge noted that the turtle was mature, of
breeding age, in peak condition and had 'probably migrated hundreds of
kilometres to reach the Whitsundays to breed, instead becoming permanently
maimed by lost fishing gear'.
The committee also received a number of submissions from organisations
and individuals who have rescued marine fauna entangled in plastic pollution.
For example, the Australian Seabird Rescue stated that:
Over 40% of the sea turtles that come into care at Australian
Seabird Rescue in Ballina are affected by plastic ingestion and/or
entanglement, many of these animals die...We have found in any estuary, 20% of
pelicans are injured by fishing line (made of plastic). Last year we had a
Green Sea Turtle (that was otherwise healthy) that had to be euthanised due to
a plastic bag wrapping tight around its flipper.
Ms Kathrina Southwell, Managing Director of the Australian Seabird
Rescue, told the committee that over the past 25 years, pelicans entangled in
fishing line have been the most common species rescued, and rehabilitated.
However, Ms Southwell noted that many birds 'have to be euthanised because they
may have a limb missing...so they cannot survive in the wild'.
An area of concern is the entanglement of animals in discarded nets.
This is a particular problem in northern Australian waters. The CSIRO and
Ghostnets Australia have undertaken work in the Gulf of Carpentaria. From their
analysis of approximately 9,000 nets intercepted in the Gulf of Carpentaria, it
was estimated that at least 15,000 turtles had been entangled. The study
examined the types of nets present in the Gulf of Carpentaria and found that
large gills nets have particularly high catch rates of turtles. The study also
concluded that given the number of nets that wash ashore in the region, the
estimated number of entangled turtles can be extended to approximately 20,000
Dr Kroon, AIMS, commented on a study which examined the impact of ghost
nets on sea-turtle populations. The aim of that project was to determine the
spatial distribution and movement of ghost nets in the Arafura Timor Sea and to
identify the demographic composition and origin of sea turtles found entangled
in those nets. It was found that derelict fishing gear enters the Arafura Timor
Sea from the north, or it is discarded locally, and that a particular type of
net made of thin twine of medium-size, the so-called GR24 nets, are more prone
to inflict harm to marine biodiversity than other types of nets. The majority
of the entangled turtles, olive ridley sea turtles, found in washed up nets
come from the Tiwi, McClure and West Papua regions—so from outside of Australia
The CSIRO also stated that entanglement of pinniped (seals and sea
lions) species in plastic pollution is common. Research has found that the
majority of pinniped entanglements in Victoria involved plastic twine or rope,
and seals become entangled in green items more than in any other colour.
Research also indicates that in general, young seals are entangled in greater
numbers than adults.
Research into entanglements with lost, abandoned or derelict fishing
gear was considered to be a priority in the paper published by Vegter el al.
as links to entanglement in derelict fishing gear 'could have considerable
financial, environmental and safety implications for fisheries management, as
the amount of fishing gear lost to the ocean is estimated to be 640,000 tonnes
Chemical accumulation and plastic-sourced chemicals
Submitters raised concerns with the potential toxic impacts of marine
Evidence was provided to the committee that marine plastic pollution serves as
both a transport medium for accumulated chemicals present in seawater, and is a
source of toxic chemicals. The chemicals include pesticides such as DDT,
polychlorinated biphenyls, and endocrine-active substances.
According to the National Toxics Network, toxicity associated with
plastics can be attributed to one or more of the following factors:
residual monomers from the manufacturing process present in the
plastic or toxic additives used in the compounding of plastic, leaching out of
partial degradation of certain plastics; and
persistent organic pollutants
(POPs) present in seawater being absorbed and concentrated in microplastic
POPs, which are almost universally present at very low concentration
levels in seawater, are absorbed, usually by microplastic fragments. Large
volumes of POPs can be absorbed by plastic, and scientists have found polypropylene
pellets with up to one million times more concentrated levels of POPs than the
The committee received evidence that 'microplastics have large surface
area to volume ratios, thus absorbing large...quantities of chemicals, which can
make them extremely toxic'.
The National Toxic Network commented that ingestion of pellets with even low
concentrations of POPs by marine organisms is likely to present a threat to
health. However, information on the extent to which ingestion of particular
chemical components contributes to organism mortality, is not readily
Some studies have been conducted on chronic dietary exposure to
low-density polyethylene plastic. These studies found that ingestion may
contribute towards the bioaccumulation
of potentially hazardous substances in fish, which can affect the health of the
These chemicals are also known to compromise immunity and cause infertility in
animals, even at very low levels.
The committee also received evidence that toxic chemicals can be
transferred into 'the tissues of marine worms and freshwater fish reducing
functions strongly linked to health biodiversity'. In addition, ingestion of
microplastics can compromise the immune systems of animals.
Dr Hardesty told the committee that some plastics, and the chemicals that
adhere to them, act as 'hormone mimics' and that 'intergenerational transfer' (from
a mother to a foetus) of some of the chemicals that are absorbed onto the
plastic or that are the constituent components of the plastics themselves, can
However, a number of witnesses commented that there 'is little known
about the long-term consequences' of exposure to plastics and accumulated
Dr Lavers commented that chemical pollution from plastic ingestion is
'still poorly understood' and noted that plastic 'acts as a vector for a whole
suite of pollutants, everything from metals to PCBs [polychlorinated biphenyl]'.
Dr Lavers went on to explain that:
...chemical pollution is much less visible and therefore much
more difficult to monitor. I think we are, at this stage, really truly
underestimating the true impact of the chemical pollution that is associated
with plastics, that morbidity effect. They are not necessarily dying, but
perhaps they are not living as long; they are not reproducing as frequently.
All of those kinds of impacts are so likely to occur, but right now we just do
not have the quantitative data to back some of those statements up.
Effects of microplastics
Evidence indicated that microplastics are now distributed throughout the
oceans, including remote areas, and, as discussed above, are ingested by marine
There is increasing concern with the effects of microplastics which
enter the marine environment. These concerns are not limited to the scientific
community; the committee received submissions from many organisations and
individuals which identified microplastics as a major issue. For example, Parks
A growing concern for park managers is the presence of
microplastics and particularly plastic nurdles in many park locations across
the state, including remote areas such as Wilsons Promontory...While the full
impacts of these materials are not well understood they have potential to cause
significant harm to feeding chicks, and being widely distributed in the
environment pose a particular risk to seabird colonies.
Birdlife Australia also provided extensive evidence of its concerns
about the effects of microplastics on shorebirds. Dr Woehler commented:
We know, full well, the complexity of marine food webs, and
we know from the work on the invertebrate sampling that has been done around
the world that many of the food species that are consumed by shorebirds in
Australia have been shown to ingest plastics. So it is a reasonable hypothesis
or prediction to make that these birds would also be susceptible to ingesting
the plastic through their food.
Despite these significant concerns, Dr Woehler stated that there was no
research on the impacts of microplastics on shorebirds:
We believed that we would find a substantial volume of
scientific literature detailing the ingestion of microplastics by shorebirds—as
coastal, intertidal feeders—around the world, particularly in Europe and North
America. But, unfortunately, we were unable to locate a single scientific study
from anywhere in the world. Such a gap is remarkable and highly significant.
The absence of such studies reinforces that there is still much to learn from
our environment, particularly the marine environment.
Dr Woehler went on to comment that Birdlife Australia considered that
'ingested microplastics and the absorbed chemicals associated with them are an
unrecognised threat to resident and migratory shorebirds in Australia and
elsewhere around the world'.
Birdlife Australia requested that the Commonwealth support directed scientific
research into the interactions between shorebirds and microplastics in
Dr Kroon also provided evidence on research being funded by AIMS which
focuses on microplastics in zooplankton samples which were collected in the
Great Barrier Reef and off Scott Reef. Plastic particles and fibres have been
found in these samples. As the samples date back to 1997, they can be used to
assess the presence and abundance of microplastics over time in these regions.
In addition, during a field campaign in November 2015, in north-west Australia,
AIMS detected small plastic particles and fibres in remote marine environments,
including the Kimberley region and offshore in the Browse and Bonaparte basins.
Further work will be undertaken to better understand the abundance and
distribution and, eventually, the sources and fates of these plastic particles
in the remote regions.
Dr Mark Browne provided the committee with a number of areas where
further research in relation to microplastic pollution was required, including
rates of accumulation, and whether population growth of organisms is being
slowed. Dr Browne added in terms of the 'unknown consequences we could be
underestimating that—and that is because of a failure to put adequate research
dollars behind these types of things'.
The committee notes that during the consultation meetings for the
revised threat abatement plan, microplastics were identified as an emerging
issue. The Department of the Environment indicated that it was generally
considered that the impact of microplastics needs to be better understood.
The threat abatement plan is discussed in detail in Chapter 4.
Possible effects of microplastics on
Many submitters voiced concerns about the possible effects of
microplastics on humans. In response, the committee noted recent research and
also sought advice from the scientists who appeared to give evidence on whether
the human consumption of seafood results in the ingestion of microplastics
carried by marine fauna, and what impact this may have on human health.
Studies have concluded that humans may ingest microplastics through the
consumption of seafood. A study conducted on Belgian mussels identified that
approximately 300 plastic particles (or 1.5 µg) would be consumed in a
300 g serving of mussels.
Similarly, another study estimated that in a 100 g serving of oysters,
50 particles would be consumed.
It is possible that
intestinal uptake of microplastics may occur in humans following the ingestion
of contaminated seafood, however this may depend on the size of the plastic
particles. Dr Browne told the committee that there was once an
assumption that ingested plastic would simply pass through the digestive
system. However there is now 'abundant evidence that when...microplastics are
inhaled or ingested they pass from the point of entry into the circulatory
There is also evidence that once in the circulatory system,
microplastics can be stored for a long time.
In humans, particles between 0.16 µm
and 150 µm have been found
to translocate through the intestinal wall, mainly through lymphatic tissue.
Dr Browne commented that medical research into drug delivery
systems has shown that the smaller the particle, the greater the rates of transfer.
Dr Browne also explained that the effects of the movement of microplastics into
the circulatory system of animals can include 'inflammation, fibrosis, breaks
in DNA, sometimes mortality and sometimes reduction in feeding behaviour'.
Further evidence was provided by Dr Hardesty who stated that
laboratory experiments which involved fish being fed microplastic found there
were 'cellular and tissue level disruptions'. Dr Hardesty explained that a
'difference in cell growth means a cancer'.
Though scientific research has identified that translocation of microplastics
in humans can occur, there is no current data available on the associated
toxicity of such translocation. Dr Hardesty noted that the effect of
microplastic ingestion on human health is a difficult issue to understand and
I would say that there is not definitive, peer-reviewed,
published literature that can address each of those steps all the- way up
through to, and including, human health. The reason for that is that you would need
to do a whole series of controlled experiments to be able to state these things
definitively, to some extent, and there are ethical considerations around doing
The committee also received evidence that chemicals accumulated on the surface
of microplastics, and chemicals used in the production of plastic may cause
adverse health effects in humans. As previously discussed, these chemicals
include substances such as phthalates and bisphenol A (BPA). These chemicals
are classified as endocrine disrupting compounds (EDCs), and the human health
implications of such chemicals have been well established. Research has linked
EDCs to cancer, male and female reproductive issues, adrenal and thyroid
disorder, neurodevelopmental issues in children, and disrupted immune function.
A number of chemicals used in fabrics such as fire retardants, and stain
and water repellents such as perfluorooctanoic acid (PFOA) and
perfluorooctanesulfonic acid (PFOS) are also of concern.
These chemicals have suspected causal links to cancer; and affect thyroid
function, reproductive health, and neurodevelopment.
These chemicals may affect both marine fauna, and subsequently humans, when
microplastic fabric fibres are consumed in the marine environment.
It should again be noted, however, that research on the human health
implications of ingesting marine fauna which have consumed these fibres has not
Impact on fisheries and shipping
The committee received evidence that marine plastic pollution has an
impact on fisheries and shipping sectors through ghost fishing, creating
navigational hazards, and providing a transport medium for invasive species.
However, evidence also noted that the impact is difficult to assess and
AIMS stated that plastic pollution such as abandoned, lost and otherwise
discarded fishing gear (ALDFG) can affect the economic outcomes of fisheries.
In particular, studies have found that abandoned fishing traps in coastal
regions can cause a reduction in annual fisheries catches of up to 5 per cent.
AIMS explained that though the economic impacts of ALDFG can vary from fishery
to fishery, it is estimated that it 'can result in annual losses of
approximately $1M AUS in individual fisheries'.
Research presented to the committee also indicated that floating plastic
pollution may facilitate 'recruitment and survival' of species such as
'barnacles, bryozoans, seasquirts, hydrozoans, sponges and bivalves'. This may
in turn allow for these species to be transported to, and then invade new
For example, the Northern Territory Seafood Council noted that in 2013, the
Asian green mussel (an invasive marine pest), was found on a ghost net
collected by Dhimurru Rangers on Bremer Island off Nhulunbuy.
Invasive marine pests can lead to an increase in operating costs
associated with biofouling on vessels and infrastructure. Invasive species also
compete for space and resources with native species, and can affect aquaculture
However, the submission from Dr Browne et al. particularly noted that
while there are confirmed reports of species travelling on marine plastic
pollution, 'there are no confirmed cases of the establishment of an invasive
species through this vector alone'.
It was noted by Vegter et al. that relatively few published
articles have focused on rafting of introduced species on plastic debris. The
researchers identified a need for additional research in how plastic pollution
contributes to the transfer of non-native species was identified.
The committee also received evidence that large abandoned ghost nets can
pose a navigational hazard to fishing vessels and other shipping, when they are
present in shipping lanes.
The Northern Territory Seafood Council commented on the potential impact
of microplastics on fisheries. The Council stated that there is potential for microplastics
entering the food chain but there is currently little understanding of the
impact on species that consume and accumulate microplastics, including humans. Of
concern is the potential in the future to microplastic contamination 'to affect
the reputation of NT seafood, currently marketed as coming from pristine remote
Impact of marine plastic on ecosystems
Marine ecosystems can be affected by marine plastic pollution through
changes of habitat and species assemblages, dispersal of marine organisms,
introduction of invasive species, and alteration of marine food webs. Damage to
sessile fauna and loss of benthic faunal cover can be caused by pollution by
marine plastic, such as fishing gear and household items. It has also been
found that along tropical coastal shorelines, marine plastic pollution has
caused significant differences in species assemblages of meiofauna, diatoms and
macrofauna. Of particular concern is the potential for dispersal on marine
plastic debris of pathogens and invasive species.
Submitters pointed to concerns about the impact of marine plastic on the
Great Barrier Reef and noted that the Great Barrier Reef Outlook Report 2014
and the Great Barrier Reef Long Term Sustainability Report 2015 have identified
marine debris as a major threatening process to the long-term health and
sustainability of the reef. The Outlook Report states that:
Marine debris, including that delivered through land-based
run-off, continues to affect the ecosystem and is of particular concern for
species of conservation concern. Many of the Region's heritage values,
including its outstanding universal value, are vulnerable to land-based run-off
through its effects on the ecosystem. In addition, water quality declines and
marine debris are likely to be diminishing the Region's natural beauty.
AIMS has conducted a qualitative risk assessment of nine different
categories of emerging contaminants, including marine plastic pollution, for
the Great Barrier Reef and Torres Strait marine ecosystems. Dr Kroon, AIMS,
commented that 'as far as the overall outcomes of the risk assessment are
concerned, marine plastics and microplastics pose one of the highest risks, if
not the highest, depending on the region, of all nine different categories of
emerging contaminants assessed'.
However, Dr Kroon commented that as the tropical marine environment
across Northern Australia is such a large area, there is uncertainty about the
abundance and distribution of marine plastics. While work has been undertaken
in some areas, such as the Great Barrier Reef and the Gulf of Carpentaria,
there is a lack of a general overview of the problem for the whole of Northern
Australia and what the long-term effects on the marine ecosystems may be.
Other submitters also acknowledged that much remains to be learnt about
the effects of marine plastic pollution on ecosystems. Dr Mark Browne et al.
noted that there is little available research which has investigated
whether plastic debris is actually impacting organisms at the population or
species level. The submission went on to state:
The consensus of these reviews is that (i) there is evidence
of ecological impacts from plastic marine debris, but over the next 5–10 years
the quantity and quality of research requires improvement to allow the risk and
relative importance of ecological impacts of plastic marine debris to be
determined with precision; (ii) sufficient evidence exists for decision-makers
to begin to mitigate problematic plastic debris now, to avoid risk of
Similarly, Dr Kroon told the committee that:
The difficulty with plastic is that it is so variable—there
are so many different chemical compositions, particle sizes and shapes. It is
not like a standard toxin, where you can compare the risk or toxicity across
many different organisms. Marine plastic pollution ranges from microplastics to
fishing nets. How do you compare the risk of one versus the other? That is one
of the big research questions, one of the big knowledge gaps that we have. That
would also progress us towards an answer as to what the ecological impacts of
marine plastics are. We know that, for individual organisms, the ingestion of
plastic material or entanglement in a fishing net can be detrimental or lethal.
But at a population level, for most organisms or species, we do not have a good
handle on what it means for population viability.
Marine plastic pollution is known to pose a serious threat to marine
fauna. The committee accepts that the ingestion of, and entanglement in marine
plastic pollution are known to cause death, and injuries including limb
amputation, starvation, intestinal rupture, and scoliosis. The committee was
concerned by the evidence that hundreds of species of fauna including birds,
turtles, cetaceans, pinnipeds and corals have been negatively affected by
ingestion and entanglement. The committee was also concerned by the statistics
indicating that thousands of individual animals have died as a result of marine
plastic pollution, particularly through entanglement with abandoned fishing
However, the committee also accepts that there remain a number of key
knowledge gaps in understanding the threat of marine plastic pollution. In
particular, the effect at the population and ecosystem levels, and the threat
posed by ingestion of microplastics by marine fauna. In addition, there is
concern that trophic transfer of microplastics may have a negative impact on
human health through the consumption of contaminated seafood.
The committee is of the view that there is an urgent need for research
to be conducted in order to remedy these knowledge gaps.
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